Mobile extensions best practices

there are many extension for ads. Unfortunately AdWords choose only some. I create callout extension, but in ad preview tool I see that my Callouts extension and Call extension didn't show.

Is it better to set some extension for desktop only and have always call extension turn on for mobile? Or should I have all extension as I can have and and be reconciled to the fact that sometimes I can't see it?

Mobile extensions best practices

Adding an extension does not mean that it will always be attached each time your ad shows. There are times that a different extension will show over another because Google has determined that that specific extension has a higher click thorough rate. However, the extensions will continue to rotate and your call extension will show.

For mobile - I would suggest creating a Call Only campaign with Call only ads in them. This way your number is in the ad all the time and potential clients can immediately call you. Also, for this campaign, you do not need any extensions as call only ads do not show them.